1. Field of the Invention
The present invention is directed to a method of monitoring mechanical or electronic check valves arranged in gas feed lines of a gas engine, to the use of the method and to a gas engine constructed for practicing the method.
2. Background of the Invention
In gas feed lines leading to a pre-chamber of a gas engine, a pressure-controlled check valve is generally installed directly adjacent to the pre-chamber. When the pressure on the side of the check valve remote of the pre-chamber is greater than the pressure on the side facing the pre-chamber—this pressure substantially corresponds to the pressure in the pre-chamber—a pressure force occurring because of the pressure difference holds the check valve open, usually against the action of a spring force. The flow cross section of the gas line is accordingly released and gas is conveyed into the pre-chamber.
However, if the combined forces of the spring force and the force exerted by the gas pressure on the side facing the pre-chamber exceed the force exerted on the side remote of the pre-chamber, the check valve closes and fluid is prevented from flowing back into the gas feed line. This situation occurs during the compression stroke of the gas engine. The compression pressure taking place in the main combustion chamber continues into the pre-chamber and the check valve is closed by the occurring pressure force. This prevents gas from flowing back into the gas feed line.
Check valves are exposed to high thermal and mechanical loads during the operation of a gas engine and therefore exhibit severe wear. After a certain operating time of the engine, the check valves are damaged, for example, due to dirt deposits, combustion residues and mechanical wear. Consequently, check valves often become leaky and, when a check valve leaks, hot, corrosive combustion gases can flow back into the gas feed line and damage other components.
Further, a leaky check valve will often cause uneven running of the engine and increased consumption of combustion gas. However, once a gas engine runs unevenly, it is often time-consuming to clarify the cause. Particularly in gas engines having a larger number of cylinders and check valves, much time must be spent to determine if one of the numerous check valves is defective. The expenditure involved in identifying a defective check valve makes the servicing of a gas engine laborious and expensive. Moreover, the time spent on servicing and, therefore, the costs incurred by servicing increase with the quantity of cylinders of the gas engine.
A method of monitoring a fuel supply installation in a vehicle which is provided for recognizing when a valve in the fuel supply installation is defective is known from DE 10 2007 002 752 A1. According to the known method, the fuel pressure and fuel temperature are detected in a portion of a fuel feed line between a fuel storage and a fuel consumer—i.e., a pre-chamber, for example—and an error signal is generated, and the fuel supply is interrupted when a change in the fuel pressure exceeds a given value during a given time period.
While it can be detected by means of the known method when a check valve is defective, the known method does not make it possible to avoid the expenditure on the servicing of the gas engine involved in identifying a defective check valve. Moreover, since a pressure sensor and a temperature sensor must be installed in the region of the gas feed lines in order for the known method to be carried out at all, it is relatively expensive and complicated to implement the known method.
Therefore, it is an object of the present invention to provide a method of monitoring check valves in a gas engine which allows the expenditure on servicing connected with the identification of a defective check valve to be reduced and which, in addition, can be implemented economically. In particular, the method according to the invention can be carried out without requiring as a precondition the installation of expensive devices in a gas engine for this purpose.